Display Device

ABSTRACT

To provide a display device that is suitable for increasing in size. To provide a display device in which display unevenness is suppressed. In a display device, a plurality of display panels are arranged to partly overlap one another. In two of the overlapping display panels, a display panel positioned on the display surface side includes a region transmitting visible light that is adjacent to a display portion, and the region transmitting visible light overlaps with a pixel of a display panel positioned on the lower side. Furthermore, in at least a display portion of the display panel placed on the lower side, an aperture ratio of the pixel overlapping with the region transmitting visible light of the display panel on the upper side is higher than an aperture ratio of another pixel.

This application is a continuation of copending U.S. application Ser.No. 14/800,033, filed on Jul. 15, 2015 which is incorporated herein byreference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

One embodiment of the present invention relates to a display device.

Note that one embodiment of the present invention is not limited to theabove technical field. The technical field of one embodiment of theinvention disclosed in this specification and the like relates to anobject, a method, or a manufacturing method. In addition, one embodimentof the present invention relates to a process, a machine, manufacture,or a composition of matter. Specifically, examples of the technicalfield of one embodiment of the present invention disclosed in thisspecification include a semiconductor device, a display device, alight-emitting device, a lighting device, a power storage device, astorage device, a method for driving any of them, and a method formanufacturing any of them.

2. Description of the Related Art

In recent years, larger display devices have been required. For example,a television device for home use (also referred to as a TV or atelevision receiver), digital signage, and a public information display(PID) are given. Larger digital signage, PID, and the like can providethe increased amount of information, and attract more attentionparticularly when used for advertisement or the like, so that theeffectiveness of the advertisement can be increased.

Examples of the display device include, typically, a liquid crystaldisplay device, a light-emitting device including a light-emittingelement such as an organic electroluminescent (EL) element or alight-emitting diode (LED), and an electronic paper performing displayby an electrophoretic method or the like.

For example, in a basic structure of an organic EL element, a layercontaining a light-emitting organic compound is provided between a pairof electrodes. By voltage application to this element, thelight-emitting organic compound can emit light. A display deviceincluding such an organic EL element needs no backlight which isnecessary for liquid crystal display devices and the like; therefore,thin, lightweight, high contrast, and low power consumption displaydevices can be obtained. Patent Document 1, for example, discloses anexample of a display device using organic EL elements.

Furthermore, Patent Document 2 discloses a flexible active matrixlight-emitting device in which an organic EL element and a transistorserving as a switching element are provided over a film substrate.

REFERENCES Patent Documents

[Patent Document 1] Japanese Published Patent Application No.2002-324673

[Patent Document 2] Japanese Published Patent Application No.2003-174153

SUMMARY OF THE INVENTION

An object of one embodiment of the present invention is to provide adisplay device that is suitable for increasing in size. Another objectof one embodiment of the present invention is to provide a displaydevice in which display unevenness is suppressed. Another object of oneembodiment of the present invention is to provide a display device thatcan display an image along a curved surface. Another object of oneembodiment of the present invention is to provide a display device thateasily achieves a reduction in thickness or weight.

Another object of one embodiment of the present invention is to providea novel display device, an electronic device, or the like.

Note that the descriptions of these objects do not disturb the existenceof other objects. In one embodiment of the present invention, there isno need to achieve all the objects. Objects other than the above objectswill be apparent from and can be derived from the description of thespecification and the like.

One embodiment of the present invention is a display device including afirst display panel and a second display panel. The first display panelincludes a first region including a first pixel and a second pixel. Thesecond display panel includes a second region, a third region, and afourth region. The second region includes a third pixel. The thirdregion has a function of transmitting visible light. The fourth regionhas a function of blocking visible light. The second pixel of the firstdisplay panel and the third region of the second display panel overlapwith each other in a region. An aperture ratio of the second pixel ishigher than an aperture ratio of the first pixel.

In the above description, it is preferable that the first display panelinclude a light-blocking layer, the first pixel include a first displayelement, and the second pixel include a second display element.Furthermore, it is preferable that the light-blocking layer include afirst opening and a second opening, the first opening and the firstdisplay element overlap with each other in a region, the second openingand the second display element overlap with each other in a region, andan area of the second opening be larger than an area of the firstopening.

In the above description, it is preferable that the first displayelement and the second display element be light-emitting elements orliquid crystal elements.

In the above description, it is preferable that the first display paneland the second display panel each have a pair of substrates and thesubstrates have flexibility.

Another embodiment of the present invention is a display deviceincluding a first display panel, a second display panel, and a thirddisplay panel. Here, the first display panel includes a first regionincluding a first pixel, a second pixel, and a third pixel. The seconddisplay panel includes a second region, a third region, and a fourthregion. The third display panel includes a fifth region, a sixth region,and a seventh region. The second region includes a fourth pixel, and thefifth region includes a fifth pixel. The third region and the sixthregion each have a function of transmitting visible light, and thefourth region and the seventh region each have a function of blockingvisible light. The second pixel of the first display panel and the thirdregion of the second display panel overlap with each other in a region.The third pixel of the first display panel, the third region of thesecond display panel, and the sixth region of the third display paneloverlap with each other in a region. An aperture ratio of the secondpixel is higher than an aperture ratio of the first pixel, and anaperture ratio of the third pixel is higher than an aperture ratio ofthe second pixel.

In the above description, it is preferable that the first display panelinclude a light-blocking layer, the first pixel include a first displayelement, the second pixel include a second display element, and thethird pixel include a third display element. Furthermore, it ispreferable that the light-blocking layer include a first opening, asecond opening, and a third opening, the first opening and the firstdisplay element overlap with each other in a region, the second openingand the second display element overlap with each other in a region, thethird opening and the third display element overlap with each other in aregion, an area of the second opening be larger than an area of thefirst opening, and an area of the third opening be larger than an areaof the second opening.

In the above description, it is preferable that the first displayelement, the second display element, and the third display element belight-emitting elements or liquid crystal elements.

In the above description, it is preferable that the first display panel,the second display panel, and the third display panel each have a pairof substrates, and the substrates have flexibility.

In the above description, it is preferable that the first display panelinclude an FPC, the FPC include a region overlapping with the secondregion of the second display panel, and the FPC be located on a sideopposite to a display surface side of the second display panel.

Another embodiment of the present invention is a display moduleincluding the display device and a touch sensor.

Another embodiment of the present invention is an electronic deviceincluding a housing and one of the display devices and the displaymodule. It is preferable that the housing include at least one of abutton, a microphone, a speaker, an antenna, and a battery.

One embodiment of the present invention can provide a display devicethat is suitable for increasing in size. One embodiment of the presentinvention can provide a display device in which display unevenness issuppressed. One embodiment of the present invention can provide adisplay device that can display an image along a curved surface. Oneembodiment of the present invention can provide a display device thateasily achieves a reduction in thickness or weight.

One embodiment of the present invention can provide a novel displaydevice (display panel) or a novel electronic device. Note that thedescription of these effects does not disturb the existence of othereffects. One embodiment of the present invention does not necessarilyachieve all the effects listed above. Other effects will be apparentfrom and can be derived from the description of the specification, thedrawings, the claims, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B illustrate a display device of one embodiment.

FIGS. 2A and 2B illustrate a display device of one embodiment.

FIGS. 3A to 3C each illustrate a display device of one embodiment.

FIGS. 4A and 4B each illustrate a display device of one embodiment.

FIGS. 5A to 5C illustrate a display panel of one embodiment.

FIG. 6 illustrates a display panel of one embodiment.

FIGS. 7A to 7D each illustrate a display panel of one embodiment.

FIGS. 8A to 8C each illustrate a display panel of one embodiment.

FIGS. 9A to 9C each illustrate a display panel of one embodiment.

FIGS. 10A to 10C illustrate a display device of one embodiment.

FIGS. 11A to 11D each illustrate a display device of one embodiment.

FIGS. 12A to 12D each illustrate a display device of one embodiment.

FIGS. 13A to 13C illustrate a display panel of one embodiment.

FIGS. 14A to 14C illustrate a display panel of one embodiment.

FIGS. 15A to 15C illustrate a touch panel of one embodiment.

FIGS. 16A to 16C illustrate a touch panel of one embodiment.

FIGS. 17A to 17C each illustrate a touch panel of one embodiment.

FIG. 18 illustrates application examples of a display device of oneembodiment.

FIGS. 19A to 19G illustrate examples of electronic devices and lightingdevices.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments will be described in detail with reference to drawings. Notethat the present invention is not limited to the description below, andit is easily understood by those skilled in the art that various changesand modifications can be made without departing from the spirit andscope of the present invention. Accordingly, the present inventionshould not be interpreted as being limited to the content of theembodiments below.

Note that in the structures of the invention described below, the sameportions or portions having similar functions are denoted by the samereference numerals in different drawings, and description of suchportions is not repeated. Further, the same hatching pattern is appliedto portions having similar functions, and the portions are notespecially denoted by reference numerals in some cases.

Note that in each drawing described in this specification, the size, thelayer thickness, or the region of each component is exaggerated forclarity in some cases. Therefore, embodiments of the present inventionare not limited to such a scale.

Note that in this specification and the like, ordinal numbers such as“first”, “second”, and the like are used in order to avoid confusionamong components and do not limit the number.

Note that the terms “film” and “layer” can be interchanged with eachother. For example, in some cases, the term “conductive film” can beused instead of the term “conductive layer,” and the term “insulatinglayer” can be used instead of the term “insulating film.”

Embodiment 1

In this embodiment, structure examples of a display device of oneembodiment of the present invention are described with reference todrawings.

One embodiment of the present invention is a display device capable ofincreasing its size by arranging a plurality of display panels to partlyoverlap one another. In two of the overlapping display panels, at leasta display panel positioned on the display surface side (upper side)includes a region transmitting visible light that is adjacent to adisplay portion. A pixel of a display panel positioned on the lower sideand the region transmitting visible light of the display panelpositioned on the upper side are provided to overlap with each other.Thus, the two of the overlapping display panels can display a seamlessand contiguous image when seen from the display surface side (in aplanar view).

Furthermore, in at least a display portion of the display panelpositioned on the lower side, an aperture ratio of the pixel overlappingwith the region transmitting visible light of the display panel on theupper side is higher than an aperture ratio of another pixel. As aresult, the luminance of an image displayed on the region overlappingwith the region transmitting visible light of the display panel on theupper side can be substantially the same as the luminance of an imagedisplayed on another region. This can be achieved even when the lighttransmittance of the region transmitting visible light is less than 100%and pixels in these regions are made to perform display at the same graylevel. Consequently, a reduction in display quality due to visuallyrecognized seams can be suppressed.

Specifically, the following structure can be employed for example.

In the description to be given below, a display device of one embodimentof the present invention and a display panel included in the displaydevice are described with reference to drawings.

[Display Panel]

FIG. 1A is a schematic top view of a display panel 100 included in adisplay device of one embodiment of the present invention.

The display panel 100 includes a display region 101, and a region 110transmitting visible light and a region 120 having a portion blockingvisible light that are adjacent to the display region 101. The displaypanel 100 is provided with a flexible printed circuit (FPC) 112 in theexample illustrated in FIG. 1A.

Here, an image can be displayed on the display region 101 even when thedisplay panel 100 is used independently. Therefore, the display panel100 is also one embodiment of a display device.

The display region 101 includes a first region 102 and a second region103. The display region 101 includes a plurality of pixels arranged inmatrix and can display an image. One or more display elements areprovided in each pixel. Typical examples of the display element includea liquid crystal element and a light-emitting element such as an organicEL element.

In the region 110, for example, a pair of substrates included in thedisplay panel 100, a sealant for sealing the display element sandwichedbetween the pair of substrates, and the like may be provided. Here, formembers provided in the region 110, materials that transmit visiblelight are used.

In the region 120, for example, a wiring electrically connected to thepixels included in the display region 101 is provided. In addition tothe wiring, driver circuits (such as a scan line driver circuit and asignal line driver circuit) for driving the pixels and a circuit such asa protective circuit may be provided. Furthermore, the region 120includes a region where a terminal electrically connected to the FPC 112(also referred to as a connection terminal), a wiring electricallyconnected to the terminal, and the like are provided.

[Display Device]

A display device 10 of one embodiment of the present invention includesa plurality of such display panels 100. FIG. 1B is a schematic top viewof the display device 10 including three display panels 100.

Hereinafter, to distinguish the display panels from each other, the samecomponents included in the display panels from each other, or the samecomponents relating to the display panels from each other, letters areadded to reference numerals of them. Unless otherwise specified, in aplurality of display panels partly overlapping with each other, “a” isadded to reference numerals for a display panel placed on the lowestside (the side opposite to the display surface side), componentsthereof, and the like, and to one or more display panels placed on theupper side of the display panel, components thereof, and the like, “b”or letters after “b” in alphabetical order are added from the lowerside. Furthermore, unless otherwise specified, in describing a structurein which a plurality of display panels is included, letters are notadded when a common part of the display panels, the components, or thelike is described.

The display device 10 in FIG. 1B includes a display panel 100 a, adisplay panel 100 b, and a display panel 100 c. Furthermore, displayregions 101 a to 101 c, regions 110 a to 110 c, regions 120 a to 120 c,first regions 102 a to 102 c, second regions 103 a to 103 c, an FPC 112c, and the like are shown in FIG. 1B.

The display panel 100 b is placed so that part of the display panel 100b overlaps an upper side (a display surface side) of the display panel100 a. Specifically, the display panel 100 b is placed so that theregion 110 b transmitting visible light of the display panel 100 boverlaps the second region 103 a in the display region 101 a of thedisplay panel 100 a, and the display region 101 a of the display panel100 a and the region 120 b blocking visible light of the display panel100 b do not overlap each other.

Furthermore, the display panel 100 c is placed so that part of thedisplay panel 100 c overlaps an upper side (a display surface side) ofthe display panel 100 b. Specifically, the display panel 100 c is placedso that the region 110 c transmitting visible light of the display panel100 c overlaps the second region 103 b in the display region 101 b ofthe display panel 100 b, and the display region 101 b of the displaypanel 100 b and the region 120 c blocking visible light of the displaypanel 100 c do not overlap each other.

The region 110 b transmitting visible light overlaps the second region103 a of the display region 101 a; thus, the whole display region 101 acan be visually recognized from the display surface side. Similarly, theregion 110 c overlaps the second region 103 b of the display region 101b; thus, the whole display region 101 b can be visually recognized fromthe display surface side. Therefore, a region where the display region101 a, the display region 101 b, and the display region 101 c areprovided seamlessly can serve as the display region 11 of the displaydevice 10.

Furthermore, the aperture ratio of a pixel in the second region 103 a ofthe display region 101 a is higher than the aperture ratio of a pixel inthe first region 102 a. Therefore, when the pixel in the second region103 a overlapping with the region 110 b transmitting visible light ofthe display panel 100 b and the pixel in the first region 102 a are madeto perform display at the same gray level, the intensity of lightemitted from the first region 102 a can be equal to the intensity oflight transmitted through the region 110 b and emitted from the secondregion 103 a. As a result, the overlap of the display panel 100 a andthe display panel 100 b is less likely to be visually recognized.Similarly, the overlap of the display panel 100 b and the display panel100 c is less likely to be visually recognized. Thus, a favorable imagewithout a seam can be displayed on the display region 11 of the displaydevice 10.

Here, the width W of the region 110 in FIG. 1A is greater than or equalto 0.1 mm and less than or equal to 200 mm, more preferably greater thanor equal to 0.5 mm and less than or equal to 150 mm, much morepreferably greater than or equal to 1 mm and less than or equal to 100mm, much more preferably greater than or equal to 2 mm and less than orequal to 50 mm. The region 110 serves as a sealing region, and as thewidth W of the region 110 is larger, the distance between an end surfaceof the display panel 100 and the display region 101 can become longer,so that entry of an impurity such as water into the display region 101from the outside can be effectively suppressed.

In particular, in this structure example, the region 110 is providedadjacent to the display region 101; thus, it is important to set thewidth W of the region 110 at an appropriate value. For example, in thecase where an organic EL element is used as the display element or thecase where a transistor (in particular, a transistor including an oxidesemiconductor) is used in a pixel, the width W of the region 110 is setto be greater than or equal to 1 mm, whereby deterioration of theorganic EL element or the transistor can be effectively suppressed;thus, reliability can be increased. Note that also in a part other thanthe region 110, the distance between the end portion of the displayregion 101 and the end surface of the display panel 100 is preferably inthe above range.

A difference between the aperture ratio of a pixel provided in the firstregion 102 and the aperture ratio of a pixel provided in the secondregion 103 may be set as appropriate depending on the transmittance ofthe region 110 transmitting visible light of the display panel over thesecond region 103. For example, when an average value of transmittancesof the region 110 with respect to light in a visible region (e.g., froma wavelength of 400 nm to a wavelength of 750 nm) is assumed to beT_(ave), the aperture ratio of the pixel in the second region 103 may bea value which is 1/T_(ave) times as large as the aperture ratio of thepixel in the first region 102, or close to (e.g., in a range of higherthan or equal to −15% and lower than or equal to 15%, preferably higherthan or equal to −10% and lower than or equal to 10%) the value.

In the case where the pixel includes sub-pixels displaying a pluralityof colors, a value of the aperture ratio of each of the sub-pixels maybe set to the above-described value, or the aperture ratios of thesub-pixels may be set individually depending on the transmittance of theregion 110 with respect to the wavelength of light emitted from eachsub-pixel. For example, in the case where the pixel includes sub-pixelsdisplaying a red color (R), a green color (G), and a blue color (B) (asub-pixel R, a sub-pixel G, and a sub-pixel B), and the transmittance ofthe region 110 with respect to red light (e.g., light with a wavelengthof 700 nm) is assumed to be T_(R), the aperture ratio of the sub-pixel Rin the second region 103 may be a value of 1/T_(R) times as large as theaperture ratio of the sub-pixel R in the first region 102, or close tothe value. The same can apply to the sub-pixel G and the sub-pixel B.

In particular, visible light with a shorter wavelength tends to beabsorbed more easily. Therefore, the aperture ratio of a sub-pixelemitting light with a short wavelength is preferably set to higher thanthe aperture ratio of a sub-pixel emitting light with a wavelengthlonger than that. For example, in three sub-pixels provided in thesecond region 103, the sub-pixel B displaying a blue color preferablyhas the aperture ratio higher than the aperture ratios of the othersub-pixels.

In FIG. 1B, all the three display panels 100 are the same. In this case,the second region 103 c in which an aperture ratio is high is visuallyrecognized in the display panel 100 c placed on the uppermost side.Therefore, when an image or the like is displayed on the display region11 of the display device 10, part of the display region 11 has highluminance in some cases.

To prevent this, the luminance of the second region 103 is preferablyreduced in the case where the second region 103 in which an apertureratio is high is not overlapped by a region 110 of another display panel100. For example, a light-transmitting component whose transmittance isthe same as that of the region 110 can be placed to overlap the displaysurface side of the second region 103. At this time, thelight-transmitting component may have a film-like shape or a plate-likeshape. As the light-transmitting component, it is preferable to use acomponent obtained in the following manner, for example: inmanufacturing the display panel 100, a component having a stacked-layerstructure similar to that of the region 110 is formed over the samesubstrate through a similar process and separated.

Alternatively, image processing for correcting the gray level of animage to be displayed may be performed only on the second region 103 toreduce the luminance of the second region 103. The maximum luminance ofthe second region 103 is higher than the maximum luminance of the firstregion 102. Therefore, image processing for lowering the gray level cancorrect the gray level so that the first region 102 and the secondregion 103 can have the same luminance.

Alternatively, for example, a component having a light-blocking propertyis provided to overlap with the second region 103 so that an imagedisplayed on the second region 103 is not visually recognized, or animage is not displayed on the second region 103. Thus, the second region103 in the display panel 100 closest to the display surface side may beexcluded from the display region 11 of the display device 10.

Alternatively, two or more kinds of display panels having differentpixel structures may be used and arranged so that the second region 103in which an aperture ratio is high is not exposed. For example, thedisplay panel 100 and a display panel 160 without the second region 103as shown in FIG. 2A are used. The display panel 160 may be used as thedisplay panel positioned on the uppermost side, as shown in FIG. 2B.

Although the plurality of display panels are arranged in one directionin the above description, a plurality of display panels may be arrangedin both longitudinal and lateral directions.

FIG. 3A shows a structure example of the display panel 100 which ispartly different from that shown in FIGS. 1A and 1B and the like. Thedisplay region 101 of the display panel 100 shown in FIG. 3A includesthe first region 102, the second region 103 in which an aperture ratiois higher than that in the first region 102, a third region 104 in whichan aperture ratio is higher than that in the second region 103, and afourth region 105 in which an aperture ratio is higher than that in thethird region 104. The region 110 transmitting visible light is providedalong two adjacent sides of the display region 101. The second region103 is provided along two adjacent sides of four sides of the displayregion 101. The third region 104 and the fourth region 105 are providedat corner portions of the display region 101.

FIG. 3B shows an example of the display device 10 in which displaypanels 100 illustrated in FIG. 3A are arranged three by three in bothlongitudinal and lateral directions. The display device 10 shown in FIG.3B includes display panels 100 a to 100 i. Note that in FIG. 3B, theregion 120 blocking visible light, the FPC 112, and the like are omittedfor simplicity, and the display region 11 and part of the region 110transmitting visible light in the periphery of the display region 11 areshown.

The display region 11 includes portions where the display regions 101 ofthe display panels are exposed, a portion 161 where one of the displaypanels 100 overlaps the display region 101, a portion 162 where two ofthe display panels 100 overlap the display region 101, and a portion 163where three of the display panels 100 overlap the display region 101.

In the portion 161, the second region 103 of the display panel 100placed on the lower side overlaps with the region 110 transmittingvisible light of the display panel 100 placed on the upper side. In theportion 162, the third region 104 of the display panel 100 placed on thelower side overlaps with the regions 110 transmitting visible light ofthe two display panels 100 placed on the upper side. In the portion 163,the fourth region 105 of the display panel 100 placed on the lower sideoverlaps with the regions 110 transmitting visible light of the threedisplay panels 100 placed on the upper side.

In the case where the plurality of display panels 100 which are thusarranged so that the number of display panels 100 overlapping thedisplay region 101 differs depending on a position in the display region101, two or more kinds of pixels having different aperture ratios arepreferably provided in the display region 101 so that a portionoverlapped by a larger number of display panels 100 includes a pixelhaving a higher aperture ratio.

Furthermore, in the nine display panels included in the display device10 shown in FIG. 3B, the display panels 100 c, 100 f, 100 g, 100 h, and100 i are placed along two sides (a side on the right side and a side onthe bottom side) opposite to the display panel 100 a positioned on thelowest side. The display panels 100 c, 100 f, 100 g, 100 h, and 100 ieach include at least one of the second region 103, the third region104, and the fourth region 105 which is not overlapped by the region 110of the other display panels 100. Such a portion can have luminancehigher than that in the other portion when an image is displayed. Toprevent this, the luminance of such a portion is preferably reduced by amethod similar to that described above.

In a portion surrounded by a dashed line in FIG. 3B, the region 110transmitting visible light of one display panel 100 overlaps the thirdregion 104 or the fourth region 105 in which an aperture ratio is higherthan that in the second region 103. Therefore, the portion can haveluminance higher than that in the other portion when an image isdisplayed. To prevent this, the luminance of the portion is preferablyreduced by a method similar to that described above.

Note that all the nine display panels 100 are the same in FIG. 3B.Alternatively, two or more kinds of display panels having differentpixel structures in the display regions 101 may be used and arranged sothat a region in which an aperture ratio is high is not exposed. Forexample, FIG. 3C illustrates the case of using a total of five kinds ofdisplay panels 100. In FIG. 3C, the display panels 100 a and 100 d havethe same structure, the display panels 100 b and 100 e have the samestructure, the display panels 100 c and 100 f have the same structure,the display panels 100 g and 100 h have the same structure, and thedisplay panel 100 i has a structure different from those of the otherdisplay panels.

Alternatively, the position of the display panel 100 placed on the upperside may be shifted, whereby the number of display panels 100overlapping the display regions 101 of the lower display panels 100 canbe reduced.

In an example shown in FIG. 4A, three display panels 100 d, 100 e, and100 f are shifted in a lateral direction. In this example, there are twokinds of portions: the portion 161 in which one display panel 100overlaps the display region 101 and the portion 162 in which two displaypanels 100 overlap the display region 101. Therefore, the fourth region105 described above is not necessarily formed, which increases designflexibility.

In the case where the display panel 100 placed on the upper side isshifted, the shape of the contour of a region in which the displayregions 101 of the display panels 100 are combined is different from arectangular shape. Since images generally have a rectangular shape, inthe case where the shape of the display region 11 of the display device10 is set to a rectangular shape as illustrated in FIG. 4A, driving maybe performed so that no image is displayed on the display regions 101 ofthe display panels 100 that are placed outside the display region 11.Here, considering the number of pixels in a region where an image is notdisplayed, more pixels than the number obtained by dividing the numberof all the pixels in the display region 11 by the number of displaypanels 100 may be provided in the display region 101 of the displaypanel 100.

Furthermore, the display region 11 of the display device 10 can have anyof a variety of shapes by changing the arrangement of a plurality ofoverlapping display panels 100. For example, FIG. 4B shows the displaydevice 10 in which the display panels 100 are arranged to have theappearance of bricks so that the contour of the display region 11 has apolygonal shape.

Note that the shape of the contour of the display region 11 is notlimited thereto, and may be a substantially circular shape, asubstantially oval shape, a polygonal shape, a polygonal shape having arounded corner portion, or the like. Note that in order to make thedisplay region 11 have a shape with a curved portion in its contour(e.g., a circular shape or an oval shape), pixels are driven such thatno image is displayed on a region placed outside the display region 11,or the region is covered with a light-blocking component.

[Pixel Included in Display Panel]

A pixel included in the display panel 100 is described below withreference to drawings.

FIG. 5A is a schematic top view of the display panel 100 describedbelow. The display panel 100 shown in FIG. 5A includes, in the displayregion 101, the first region 102 including a first pixel 172 and thesecond region 103 including a second pixel 173 having an aperture ratiohigher than that of the first pixel 172.

FIG. 5B is a schematic enlarged view of the first region 102 and thesecond region 103 when seen from the display surface side.

The first region 102 includes the first pixel 172. The second region 103includes the second pixel 173. The first pixel 172 and the second pixel173 each include the sub-pixel R, the sub-pixel G, and the sub-pixel B.The sub-pixel R is typically a pixel displaying a red color. Thesub-pixel G is typically a pixel displaying a green color. The sub-pixelB is typically a pixel displaying a blue color. A light-blocking layer171 having openings in regions overlapping with the sub-pixels isprovided. As shown in FIG. 5B, the size of each sub-pixel in the secondpixel 173 is larger than the size of each sub-pixel in the first pixel172.

FIG. 5C is a schematic cross-sectional view of one sub-pixel in thefirst pixel 172 and one sub-pixel in the second pixel 173.

Each sub-pixel shown in FIG. 5C includes a transistor 175, an insulatinglayer 176, an insulating layer 177, a light-emitting element 180, thelight-blocking layer 171, a coloring layer 185, and a sealing layer 186.The light-emitting element 180 includes an electrode 181 having areflecting property, an electrode 183 having a light-transmittingproperty, and an EL layer 182 containing a light-emitting organiccompound between the electrode 181 and the electrode 183. The electrode181 is electrically connected to one of a source and a drain of thetransistor 175 through an opening provided in the insulating layer 176.The insulating layer 177 is provided to cover an end portion of theelectrode 181 and has an opening at a position overlapping with theelectrode 181. The size of the opening in the insulating layer 177 overthe electrode 181 is substantially the same as the size of thelight-emitting element 180.

In FIG. 5C, the size of the opening in the light-blocking layer 171 inthe sub-pixel of the first pixel 172 is different from the size of theopening in the light-blocking layer 171 in the sub-pixel of the secondpixel 173. That is, in the sub-pixel of the first pixel 172, part of thelight-blocking layer 171 covers part of the light-emitting element 180.In such a structure, portions other than the light-blocking layer 171can be shared, which increases design flexibility. Furthermore, bychanging only a photomask for forming the light-blocking layer 171, adisplay panel having different pixel structures as described above canbe manufactured.

In the cross section shown in FIG. 5C, a width W2 of the opening in thelight-blocking layer 171 that overlaps with the sub-pixel of the secondpixel 173 is larger than a width W1 of the opening in the light-blockinglayer 171 that overlaps with the sub-pixel of the first pixel 172. InFIG. 5B, the shapes of the sub-pixels (here, the shapes of the openingsin the light-blocking layer 171) in the second pixel 173 are obtained byenlarging the lateral and longitudinal widths of the sub-pixels in thefirst pixel 172 in approximately the same proportion. However, theshapes of the sub-pixels are not limited thereto. The sub-pixel may haveany shape as long as the widths of the sub-pixels (e.g., the widths ofthe openings in the light-blocking layer 171) are different from eachother in at least an arbitrary cross section. For example, a sub-pixelin one pixel may have a shape in which the shape of a sub-pixel in theother pixel is enlarged or reduced in one direction.

In the example shown here, the three sub-pixels in the pixel have thesame size, but the sub-pixels are not limited thereto. The sizes of thesub-pixels (e.g., the sizes of the light-emitting elements 180) may bedifferent from each other. Furthermore, in the example shown here, thethree sub-pixels in one of the first region 102 and the second region103 have shapes in which the shapes of the three sub-pixels in the otherare enlarged or reduced in the same proportion, but the shapes of thethree sub-pixels may be enlarged or reduced in different proportions.

Light emitted from the sub-pixels is described. Since the transistor 175and the light-emitting element 180 are connected in series, a currentthat flows between the source and the drain of the transistor 175 flowsthrough the light-emitting element 180. The light-emitting element 180supplied with a given amount of current emits light with a givenluminance. In the first pixel 172, part of the light-emitting element180 is covered by the light-blocking layer 171, and therefore, part oflight travelling in straight lines from the light-emitting element 180toward the display surface side is blocked by the light-blocking layer171. In the second pixel 173, most of light travelling in straight linesfrom the light-emitting element 180 toward the display surface side isemitted to the display surface side. Therefore, the intensity of lightemitted from the sub-pixel in the second pixel 173 is higher than theintensity of light emitted from the sub-pixel in the first pixel 172even when the sub-pixels are driven by the same amount of current. Thisenables a circuit for driving pixels (including the transistors 175) tobe shared.

In the example shown here, two regions (the first region 102 and thesecond region 103) are provided in the display region 101 of the displaypanel 100, but three or more regions differing in aperture ratio may beprovided as described above. For example, FIG. 6 shows a structureincluding the first region 102 having the first pixel 172, the secondregion 103 having the second pixel 173 with an aperture ratio higherthan that of the first pixel 172, and the third region 104 having thethird pixel 174 with an aperture ratio higher than that of the secondpixel 173.

The structure of the pixel provided in each region of the display region101 may be any of a variety of structures without being limited to thosedescribed above.

FIG. 7A shows a structure in which, in the sub-pixels of the pixel 173in the second region 103, only the sub-pixel B is larger than thesub-pixel of the pixel 172 in the first region 102. In this manner, theaperture ratio of only a given sub-pixel may be changed.

FIGS. 7B and 7C illustrate the cases where each pixel includes asub-pixel Y in addition to the sub-pixel R, the sub-pixel G, and thesub-pixel B. The sub-pixel Y is typically a pixel displaying a yellowcolor. Such a structure including sub-pixels displaying four or morecolors can achieve low power consumption. Note that a sub-pixel Wdisplaying a white color may be used instead of the sub-pixel Y, or apixel including sub-pixels displaying five colors where the sub-pixel Wis added to the structure may be used.

In FIGS. 7A to 7C, FIGS. 5A to 5C, FIG. 6, and the like, the sub-pixelsR, G, B, and Y have a stripe arrangement. However, the sub-pixels arenot limited to the arrangement. For example, in FIG. 7D, the sub-pixelsR and the sub-pixels G are alternated in one direction and thesub-pixels B and the sub-pixels Y are alternated in one direction.

Next, a cross-sectional structure is described. In FIG. 5C, the size ofthe light-blocking layer 171 is changed to form pixels having differentaperture ratios, but another method may be employed to form pixelshaving different aperture ratios.

In FIG. 8A, schematic cross-sectional views of two sub-pixels havingdifferent aperture ratios are shown in a manner similar to that of FIG.5C. In an example shown in FIG. 8A, two sub-pixels having differentaperture ratios are obtained by making the two sub-pixels differ in thesize of the opening in the insulating layer 177, not by making the twosub-pixels differ in the size of the light-blocking layer 171. Also inthe case of using such a structure, a display panel having differentpixel structures can be manufactured by changing only a photomask forforming the insulating layer 177.

Note that in the structure shown in FIG. 8A, the areas of thelight-emitting elements 180 are different from each other; therefore,when the same amount of current is supplied to the light-emittingelements 180, the light-emitting elements 180 have different currentdensities. As a result, when driving is performed using the same amountof current, the light-emitting element 180 in the sub-pixel having alower aperture ratio emits light with higher luminance in some cases. Toprevent this, it is preferable to perform driving so that the currentdensities in the light-emitting elements 180 are equal to each other intwo sub-pixels having different aperture ratios.

As shown in FIG. 8B, sub-pixels having different aperture ratios may beobtained by making the sub-pixels differ in both the size of the openingin the insulating layer 177 and the size of the opening in thelight-blocking layer 171. Such a structure enables sub-pixels havingdifferent aperture ratios to exhibit the same viewing angle dependence.

In the structures shown in FIG. 5C and FIGS. 8A and 8B, a light-emittingelement emitting white light (e.g., light having two or more peaks in awavelength range of 450 nm to 700 nm or light having intensity in awavelength range of 450 nm to 700 nm) is preferably used mainly as thelight-emitting element 180. White light emitted from the light-emittingelement 180 is transmitted through the coloring layer 185, whereby lightof a specific color is extracted. When the coloring layers 185 ofdifferent colors are provided in the sub-pixels, the display panel 100can achieve full-color display.

Note that the light-emitting elements emitting light of different colorsmay be formed in sub-pixels for different colors to achieve full-colordisplay. FIG. 8C shows an example in which a light-emitting element 180Rincluding an EL layer 182R emitting red light is provided in asub-pixel. In this case, a structure without the coloring layer 185 maybe employed as shown in FIG. 8C because the EL layer 182R emits redlight.

In the above-described cases, a display element is a light-emittingelement, but not limited thereto, and may be a liquid crystal element orthe like. FIG. 9A shows the case of including a liquid crystal element190 using a vertical alignment (VA) mode.

The liquid crystal element 190 included in each sub-pixel shown in FIG.9A includes an electrode 191 electrically connected to one of the sourceand the drain of the transistor 175, an electrode 193, and a liquidcrystal 192 between the electrode 191 and the electrode 193. Althoughnot shown here, two polarizing plates between which the liquid crystalelement 190 is provided and a light source such as a backlight may befurther included. Furthermore, as shown in FIG. 9A, a spacer 196 may beprovided over the insulating layer 177.

In the example shown in FIG. 9A, sub-pixels having different apertureratios are obtained by making the sub-pixels differ in the size of theopening in the light-blocking layer 171. In the example shown in FIG.9B, sub-pixels having different aperture ratios are obtained by makingthe sub-pixels differ in both the size of the opening in thelight-blocking layer 171 and the size of the opening in the insulatinglayer 177. The orientation of liquid crystals in the liquid crystalelement 190 can be controlled by electric field intensity. Therefore,even in the liquid crystal elements 190 having different areas, theorientations of liquid crystals when voltages at the same level areapplied between electrodes can be substantially the same. Thus, theintensity of light transmitted through the sub-pixel can be varieddepending on the size of the liquid crystal element 190 even when thesub-pixels are driven with voltages at the same level.

FIG. 9C shows the case where the liquid crystal element 190 using afringe field switching (FFS) mode is included. The liquid crystalelement 190 shown in FIG. 9C includes the electrode 191, the electrode193 over the electrode 191 with an insulating layer 194 providedtherebetween, and the liquid crystal 192. The electrode 193 has acomb-like shape or a shape provided with a slit. In the example shown inFIG. 9C, sub-pixels having different aperture ratios are obtained bymaking the sub-pixels differ in both the opening in the light-blockinglayer 171 and the opening in the insulating layer 177 and differ in theshape of the electrode 193.

Although the liquid crystal element using a VA mode and the liquidcrystal element using an FFS mode are described above, a twisted nematic(TN) mode, an in-plane-switching (IPS) mode, an axially symmetricaligned micro-cell (ASM) mode, an optically compensated birefringence(OCB) mode, a ferroelectric liquid crystal (FLC) mode, anantiferroelectric liquid crystal (AFLC) mode, or the like can be used.

As the liquid crystal, a thermotropic liquid crystal, a low-molecularliquid crystal, a high-molecular liquid crystal, a ferroelectric liquidcrystal, an anti-ferroelectric liquid crystal, a polymer dispersedliquid crystal (PDLC), or the like can be used. Moreover, a liquidcrystal exhibiting a blue phase is preferably used because an alignmentfilm is not needed and a wide viewing angle is obtained in that case.

[Other Configuration Examples of Display Device]

Examples of using a flexible display panel as the display panel 100 aredescribed.

FIG. 10A shows an example of the display panel 100 which can be used ina display device to be described below. The display region 101 of thedisplay panel 100 shown in FIG. 10A includes the first region 102, thesecond region 103, and the third region 104.

FIG. 10B is a schematic perspective view of the display device 10 inwhich the display panels 100 are arranged two by two in bothlongitudinal and lateral directions. FIG. 10C is a schematic perspectiveview of the display device 10 when seen from a side opposite to thedisplay surface side. Furthermore, the display panels 100 a to 100 d,the display regions 101 a to 101 c, a display region 101 d, the regions110 a to 110 c, a region 110 d, the regions 120 b and 120 c, a region120 d, FPCs 112 a, 112 b, and 112 d, the FPC 112 c, and the like areshown in FIGS. 10B and 10C.

In FIGS. 10B and 10C, part of the region 110 b of the display panel 100b and a region along a short side of the display region 101 a of thedisplay panel 100 a overlap with each other. In addition, part of theregion 110 c of the display panel 100 c and a region along a long sideof the display region 101 a of the display panel 100 a overlap with eachother. Moreover, a region 110 d of a display panel 100 d overlaps both aregion along a long side of the display region 101 b of the displaypanel 100 b and a region along a short side of the display region 101 cof the display panel 100 c.

Therefore, as illustrated in FIG. 10B, a region where the displayregions 101 a to 101 d are placed seamlessly can serve as the displayregion 11 of the display device 10. Note that FIG. 10B shows the casewhere display panels including different pixel structures are used asthe display panels 100 a to 100 d and arranged so that a region having ahigh aperture ratio is not exposed.

Here, it is preferable that a flexible material be used for the pair ofsubstrates included in the display panel 100 and the display panel 100have flexibility. Thus, as in the display panel 100 a shown in FIGS. 10Band 10C, a region near an FPC 112 a of the display panel 100 a can bebent so that part of the display panel 100 a and part of the FPC 112 acan be placed under the display region 101 b of the display panel 100 b.As a result, the FPC 112 a can be placed without physical interferencewith the rear surface of the display panel 100 b. Furthermore, when thedisplay panel 100 a and the display panel 100 b overlap and are fixed toeach other, it is not necessary to consider the thickness of the FPC 112a; thus, the difference in height between the top surface of the region110 b of the display panel 100 b and the top surface of the displaypanel 100 a can be reduced. This can make an end portion of the displaypanel 100 b over the display region 101 a less noticeable.

Moreover, each display panel 100 has flexibility, whereby the displaypanel 100 b can be curved gently so that the top surface of the displayregion 101 b of the display panel 100 b and the top surface of thedisplay region 101 a of the display panel 100 a are equal to each otherin height. Thus, the heights of the display regions can be equal to eachother except in the vicinity of the region where the display panel 100 aand the display panel 100 b overlap each other, so that the displayquality of an image displayed on the display region 11 of the displaydevice 10 can be improved.

The relation between the display panel 100 a and the display panel 100 bis taken as an example in the above description, and the same can applyto the relation between any two adjacent display panels (e.g., betweenthe display panel 100 c and the display panel 100 d).

Furthermore, to reduce the step between two adjacent display panels 100,the thickness of the display panel 100 is preferably small. For example,the thickness of the display panel 100 is preferably less than or equalto 1 mm, further preferably less than or equal to 300 μm, still furtherpreferably less than or equal to 100 μm.

FIG. 11A is a schematic cross-sectional view when the two display panels100 are bonded to each other. In an example shown in FIG. 11A, the FPC112 a and an FPC 112 b are connected to the display surface side of thedisplay panel 100 a and the display surface side of the display panel100 b, respectively.

Alternatively, as illustrated in FIG. 11B, the FPC 112 a and the FPC 112b may be connected to the side opposite to the display surface side ofthe display panel 100 a and the side opposite to the display surfaceside of the display panel 100 b, respectively. In this structure, theend portion of the display panel 100 a positioned on the lower side canbe attached to the rear surface of the display panel 100 b; thus, theattachment area can be increased and the mechanical strength of theattached portion can be increased.

Alternatively, as illustrated in FIGS. 11C and 11D, a light-transmittingresin layer 131 may be provided to cover the top surfaces of the displaypanel 100 a and the display panel 100 b. Specifically, the resin layer131 is preferably provided to cover the display regions of the displaypanels 100 a and 100 b and a region where the display panel 100 a andthe display panel 100 b overlap.

By providing the resin layer 131 over the plurality of display panels100, the mechanical strength of the display device 10 can be increased.In addition, the resin layer 131 is formed to have a flat surface,whereby the display quality of an image displayed on the display region11 can be increased. For example, when a coating apparatus such as aslit coater, a curtain coater, a gravure coater, a roll coater, or aspin coater is used, the resin layer 131 with high flatness can beformed.

Furthermore, a difference in refractive index between the resin layer131 and the substrate on the display surface side of the display panel100 is preferably less than or equal to 20%, further preferably lessthan or equal to 10%, still further preferably less than or equal to 5%.By using the resin layer 131 having such a refractive index, light canbe efficiently extracted outside. In addition, the resin layer 131 withsuch a refractive index is provided to cover a step portion between thedisplay panel 100 a and the display panel 100 b, whereby the stepportion is not easily recognized visually, and the display quality of animage displayed on the display region 11 of the display device can beincreased.

As a material used for the resin layer 131, for example, an organicresin such as an epoxy resin, an aramid resin, an acrylic resin, apolyimide resin, a polyamide resin, or a polyamide-imide resin can beused.

Alternatively, as illustrated in FIGS. 12A and 12B, a protectivesubstrate 132 is preferably provided over the display device 10 with theresin layer 131 provided therebetween. Here, the resin layer 131 mayserve as a bonding layer for bonding the protective substrate 132 to thedisplay device 10. With the protective substrate 132, the surface of thedisplay device 10 can be protected, and moreover, the mechanicalstrength of the display device 10 can be increased. For the protectivesubstrate 132 in a region overlapping at least the display region 11, alight-transmitting material is used. Furthermore, the protectivesubstrate 132 in a region other than the region overlapping the displayregion 11 may have a light-blocking property not to be visuallyrecognized.

The protective substrate 132 may have a function of a touch panel. Inthe case where the display panel 100 is flexible and can be bent, theprotective substrate 132 is also preferably flexible.

Furthermore, a difference in refractive index between the protectivesubstrate 132 and the substrate on the display surface side of thedisplay panel 100 or the resin layer 131 is preferably less than orequal to 20%, further preferably less than or equal to 10%, stillfurther preferably less than or equal to 5%.

As the protective substrate 132, a plastic substrate that is formed as afilm, for example, a plastic substrate made from polyimide (PI), anaramid, polyethylene terephthalate (PET), polyethersulfone (PES),polyethylene naphthalate (PEN), polycarbonate (PC), nylon,polyetheretherketone (PEEK), polysulfone (PSF), polyetherimide (PEI),polyarylate (PAR), polybutylene terephthalate (PBT), a silicone resin,and the like can be used. The protective substrate 132 is preferablyflexible. The protective substrate 132 includes a fiber or the like(e.g., a prepreg). Furthermore, a base material is not limited to theresin film, and a transparent nonwoven fabric formed by processing pulpinto a continuous sheet, a sheet including an artificial spider's threadfiber containing protein called fibroin, a complex in which thetransparent nonwoven fabric or the sheet and a resin are mixed, a stackof a resin film and a nonwoven fabric containing a cellulose fiber whosefiber width is 4 nm or more and 100 nm or less, or a stack of a resinfilm and a sheet including an artificial spider's thread fiber may beused.

Alternatively, as illustrated in FIGS. 12C and 12D, a resin layer 133may be provided on a surface opposite to the display surface sides ofthe display panel 100 a and the display panel 100 b, and a protectivesubstrate 134 may be provided with the resin layer 133 provided betweenthe protective substrate 134 and each of the display panels 100 a and100 b. In this manner, the display panels 100 a and 100 b are sandwichedbetween the two protective substrates, whereby the mechanical strengthof the display device 10 can be further increased. Furthermore, when thethicknesses of the resin layers 131 and 133 are substantially equal toeach other, and for the protective substrates 132 and 134, materialshaving thicknesses which are substantially equal to each other are used,the plurality of display panels 100 can be located at the center of thestack. For example, when the stack including the display panel 100 isbent, by locating the display panel 100 at the center in the thicknessdirection, stress in the lateral direction applied to the display panel100 by bending can be relieved, so that damage can be prevented.

As illustrated in FIGS. 12C and 12D, an opening portion for extractingthe FPC 112 a is preferably provided in the resin layer 133 and theprotective substrate 134, which are located on the rear surface sides ofthe display panels 100 a and 100 b. At this time, by providing the resinlayer 133 to cover part of the FPC 112 a, the mechanical strength at aconnection portion between the display panel 100 a and the FPC 112 a canbe increased, and defects such as peeling of the FPC 112 a can besuppressed. Similarly, the resin layer 133 is preferably provided tocover part of the FPC 112 b.

Note that the resin layer 133 and the protective substrate 134, whichare provided on the side opposite to the display surface side, do notnecessarily have a light-transmitting property, and a material whichabsorbs or reflects visible light may be used. When the resin layers 133and 131, or the protective substrates 134 and 132 have the samematerials, manufacturing cost can be reduced.

[Structure Examples of Region Transmitting Visible Light and RegionBlocking Visible Light]

Next, structure examples of the region 110 transmitting visible light ofthe display panel 100, the vicinity of the region 110, the region 120blocking visible light, and the vicinity of the region 120 aredescribed.

FIG. 13A is a schematic top view in which a region P in FIG. 10A isenlarged, and FIG. 13B is a schematic top view in which a region Q inFIG. 10A is enlarged.

As illustrated in FIG. 13A, in the display region 101, a plurality ofpixels 141 are arranged in matrix. In the case where the display panel100 capable of full color display with three colors of red, blue, andgreen is formed, the pixel 141 corresponds to a sub-pixel capable ofdisplaying any of the three colors. Alternatively, a pixel capable ofdisplaying white or yellow in addition to the three colors may beprovided. A region including the pixels 141 corresponds to the displayregion 101.

A wiring 142 a and a wiring 142 b are electrically connected to onepixel 141. The plurality of wirings 142 a each intersect with the wiring142 b, and is electrically connected to a circuit 143 a. The pluralityof wirings 142 b is electrically connected to a circuit 143 b. One ofthe circuits 143 a and 143 b can function as a scan line driver circuit,and the other can function as a signal line driver circuit. A structurewithout one of the circuits 143 a and 143 b or both of them may beemployed.

In FIG. 13A, a plurality of wirings 145 electrically connected to thecircuit 143 a or the circuit 143 b is provided. The wiring 145 iselectrically connected to the FPC 112 in an unillustrated region and hasa function of supplying a signal from the outside to the circuits 143 aand 143 b.

In FIG. 13A, a region including the circuit 143 a, the circuit 143 b,the plurality of wirings 145, and the like corresponds to the region 120blocking visible light.

In FIG. 13B, a region outside the pixel 141 provided closest to the endcorresponds to the region 110 transmitting visible light. The region 110does not include the members blocking visible light, such as the pixel141, the wiring 142 a, and the wiring 142 b. Note that in the case wherepart of the pixel 141, the wiring 142 a, or the wiring 142 b transmitsvisible light, the part of the pixel 141, the wiring 142 a, or thewiring 142 b may be provided to extend to the region 110.

Here, the width W of the region 110 indicates the narrowest width of theregion 110 provided in the display panel 100 in some cases. In the casewhere the width W of the region 110 varies depending on the positions,the shortest length can be referred to as the width W. In FIG. 13B, thedistance between the pixel 141 and the end surface of the substrate(that is, the width W of the region 110) in the longitudinal directionis the same as that in the lateral direction.

FIG. 13C is a schematic cross-sectional view taken along line A1-A2 inFIG. 13B. The display panels 100 include a pair of light-transmittingsubstrates (a substrate 151 and a substrate 152). The substrate 151 andthe substrate 152 are bonded to each other with a bonding layer 153.Here, the substrate on which the pixel 141, the wiring 142 b, and thelike are formed is referred to as the substrate 151.

As illustrated in FIGS. 13B and 13C, in the case where the pixel 141 ispositioned closest to the end of the display region 101, the width ofthe region 110 transmitting visible light is the distance between theend portion of the substrate 151 or the substrate 152 and the endportion of the pixel 141.

Note that the end portion of the pixel 141 refers to the end portion ofthe member that is positioned closest to the end and blocks visiblelight in the pixel 141. In the case where a light-emitting elementincluding a layer containing a light-emitting organic compound between apair of electrodes (also referred to as an organic EL element) is usedas the pixel 141, the end portion of the pixel 141 may be any of the endportion of the lower electrode, the end portion of the layer containinga light-emitting organic compound, and the end portion of the upperelectrode.

FIG. 14A shows the case where the position of the wiring 142 a isdifferent from that in FIG. 13B. FIG. 14B is a schematic cross-sectionalview taken along line B1-B2 in FIG. 14A, and FIG. 14C is a schematiccross-sectional view taken along line C1-C2 in FIG. 14A.

As illustrated in FIGS. 14A to 14C, in the case where the wiring 142 ais positioned closest to the end of the display region 101, the width Wof the region 110 transmitting visible light is the distance between theend portion of the substrate 151 or the substrate 152 and the endportion of the wiring 142 a. In the case where the wiring 142 atransmits visible light, the region 110 may include a region where thewiring 142 a is provided.

Note that one embodiment of the present invention is not limited to theabove examples. For example, in the case where the plurality of displaypanels 100 are arranged to partly overlap one another, the pixels havinghigher aperture ratios are overlapped by a larger number of displaypanels 100 in the above-described examples. However, the pixels do notnecessarily have higher aperture ratios in some cases. For example, thepixels may have the same aperture ratio. Alternatively, the pixels maybe made differ in the luminance of light emitted therefrom. For example,a pixel overlapped by a plurality of display panels is made to emitlight with high luminance. This allows a viewer of the display device tosee a displayed image as if a place overlapped by the display panel anda place not overlapped by the display panel emitted light of the sameluminance.

At least part of this embodiment can be implemented in combination withany of the embodiments described in this specification as appropriate.

Embodiment 2

In this embodiment, a display panel which can be used in a displaydevice of one embodiment of the present invention is described withreference to drawings. Here, as an example of the display panel, a touchpanel having a function as a touch sensor is described.

FIG. 15A is a top view illustrating a structure of a touch panel thatcan be used in a display device of one embodiment of the presentinvention. FIG. 15B is a cross-sectional view taken along line A-B andline C-D in FIG. 15A. FIG. 15C is a cross-sectional view taken alongline E-F in FIG. 15A.

[Top View]

A touch panel 300 described as an example in this embodiment includes adisplay portion 301 (see FIG. 15A).

The display portion 301 includes a plurality of pixels 302 and aplurality of imaging pixels 308. The imaging pixels 308 can sense atouch of a finger or the like on the display portion 301. Thus, a touchsensor can be formed using the imaging pixels 308.

Each of the pixels 302 includes a plurality of sub-pixels (e.g., asub-pixel 302R). In addition, the sub-pixels are provided withlight-emitting elements and pixel circuits that can supply electricpower for driving the light-emitting elements.

The pixel circuits are electrically connected to wirings through whichselection signals are supplied and wirings through which image signalsare supplied.

Furthermore, the touch panel 300 is provided with a scan line drivercircuit 303 g(1) that can supply selection signals to the pixels 302 andan image signal line driver circuit 303 s(1) that can supply imagesignals to the pixels 302.

The imaging pixels 308 include photoelectric conversion elements andimaging pixel circuits that drive the photoelectric conversion elements.

The imaging pixel circuits are electrically connected to wirings throughwhich control signals are supplied and wirings through which powersupply potentials are supplied.

Examples of the control signals include a signal for selecting animaging pixel circuit from which a recorded imaging signal is read, asignal for initializing an imaging pixel circuit, and a signal fordetermining the time taken for an imaging pixel circuit to sense light.

The touch panel 300 is provided with an imaging pixel driver circuit 303g(2) that can supply control signals to the imaging pixels 308 and animaging signal line driver circuit 303 s(2) that reads imaging signals.

The touch panel 300 includes the region 110 transmitting visible lightalong two sides of the display portion 301.

[Cross-Sectional View]

The touch panel 300 includes a substrate 310 and a counter substrate 370that faces the substrate 310 (see FIG. 15B).

The substrate 310 is a stack in which a flexible substrate 310 b, abarrier film 310 a that prevents diffusion of impurities to thelight-emitting elements, and an adhesive layer 310 c that bonds thebarrier film 310 a to the substrate 310 b are stacked.

The counter substrate 370 is a stack including a flexible substrate 370b, a barrier film 370 a that prevents diffusion of impurities to thelight-emitting elements, and an adhesive layer 370 c that attaches thebarrier film 370 a to the substrate 370 b (see FIG. 15B).

A sealant 360 attaches the counter substrate 370 to the substrate 310.The sealant 360 has a refractive index higher than that of air. Thesealant 360 serves as a layer which optically attaches two members(here, the counter substrate 370 and the substrate 310) between whichthe sealant 360 is sandwiched (hereinafter also referred to as anoptical adhesive layer). The pixel circuits and the light-emittingelements (e.g., a light-emitting element 350R) are provided between thesubstrate 310 and the counter substrate 370.

[Pixel Structure]

Each of the pixels 302 includes a sub-pixel 302R, a sub-pixel 302G, anda sub-pixel 302B (see FIG. 15C). The sub-pixel 302R includes alight-emitting module 380R, the sub-pixel 302G includes a light-emittingmodule 380G, and the sub-pixel 302B includes a light-emitting module380B.

For example, the sub-pixel 302R includes the light-emitting element 350Rand a pixel circuit that can supply electric power to the light-emittingelement 350R and includes a transistor 302 t (see FIG. 15B). Thelight-emitting module 380R includes the light-emitting element 350R andan optical element (e.g., a coloring layer 367R).

The light-emitting element 350R includes a lower electrode 351R, anupper electrode 352, and a layer 353 containing a light-emitting organiccompound between the lower electrode 351R and the upper electrode 352(see FIG. 15C).

The layer 353 containing a light-emitting organic compound includes alight-emitting unit 353 a, a light-emitting unit 353 b, and anintermediate layer 354 between the light-emitting units 353 a and 353 b.

The light-emitting module 380R includes the coloring layer 367R on thecounter substrate 370. The coloring layer transmits light with aparticular wavelength and is, for example, a layer that selectivelytransmits red, green, or blue light. Alternatively, a region thattransmits light emitted from the light-emitting element as it is may beprovided.

The light-emitting module 380R, for example, includes the sealant 360that is in contact with the light-emitting element 350R and the coloringlayer 367R.

The coloring layer 367R is positioned in a region overlapping with thelight-emitting element 350R. Accordingly, part of light emitted from thelight-emitting element 350R passes through the sealant 360 that alsoserves as an optical adhesive layer and through the coloring layer 367Rand is emitted to the outside of the light-emitting module 380R asindicated by arrows in FIGS. 15B and 15C.

Note that although the case where the light-emitting element is used asa display element is described here, one embodiment of the presentinvention is not limited thereto.

In this specification and the like, for example, a display element, adisplay device or a display panel which is a device including a displayelement, a light-emitting element, and a light-emitting device which isa device including a light-emitting element can employ a variety ofmodes or can include a variety of elements. The display element, thedisplay device, the display panel, the light-emitting element, or thelight-emitting device includes at least one of an electroluminescent(EL) element (e.g., an EL element including organic and inorganicmaterials, an organic EL element, or an inorganic EL element), an LED(e.g., a white LED, a red LED, a green LED, or a blue LED), a transistor(a transistor that emits light depending on current), an electronemitter, a liquid crystal element, electronic ink, an electrophoreticelement, a grating light valve (GLV), a plasma display panel (PDP), adisplay element using micro electro mechanical system (MEMS), a digitalmicromirror device (DMD), a digital micro shutter (DMS), MIRASOL®, aninterferometric modulator display (IMOD) element, a MEMS shutter displayelement, an optical-interference-type MEMS display element, anelectrowetting element, a piezoelectric ceramic display, a displayelement including a carbon nanotube, and the like. Other than the above,display media whose contrast, luminance, reflectivity, transmittance, orthe like is changed by an electrical or magnetic effect may be included.Note that examples of display devices using EL elements include an ELdisplay. Examples of display devices including electron emitters includea field emission display (FED) and an SED-type flat panel display (SED:surface-conduction electron-emitter display). Examples of displaydevices using liquid crystal elements include a liquid crystal display(e.g., a transmissive liquid crystal display, a transflective liquidcrystal display, a reflective liquid crystal display, a direct-viewliquid crystal display, and a projection liquid crystal display).Examples of a display device including electronic ink, Electronic LiquidPowder®, or electrophoretic elements include electronic paper. In thecase of a transflective liquid crystal display or a reflective liquidcrystal display, some or all of pixel electrodes function as reflectiveelectrodes. For example, some or all of pixel electrodes are formed tocontain aluminum, silver, or the like. In such a case, a memory circuitsuch as an SRAM can be provided under the reflective electrodes, leadingto lower power consumption. Note that in the case of using an LED,graphene or graphite may be provided under an electrode or a nitridesemiconductor of the LED. Graphene or graphite may be a multilayer filmin which a plurality of layers are stacked. As described above,provision of graphene or graphite enables easy formation of a nitridesemiconductor film thereover, such as an n-type GaN semiconductor layerincluding crystals. Furthermore, a p-type GaN semiconductor layerincluding crystals or the like can be provided thereover, and thus theLED can be formed. Note that an AlN layer may be provided between then-type GaN semiconductor layer including crystals and graphene orgraphite. The GaN semiconductor layers included in the LED may be formedby MOCVD. Note that when the graphene is provided, the GaN semiconductorlayers included in the LED can also be formed by a sputtering method.

[Touch Panel Structure]

The touch panel 300 includes a light-blocking layer 367BM on the countersubstrate 370. The light-blocking layer 367BM is provided so as tosurround the coloring layer (e.g., the coloring layer 367R).

The touch panel 300 includes an anti-reflective layer 367 p positionedin a region overlapping with the display portion 301. As theanti-reflective layer 367 p, a circular polarizing plate can be used,for example.

The touch panel 300 includes an insulating film 321. The insulating film321 covers the transistor 302 t. Note that the insulating film 321 canbe used as a layer for planarizing unevenness caused by the pixelcircuits. An insulating film on which a layer that can prevent diffusionof impurities to the transistor 302 t and the like is stacked can beused as the insulating film 321.

The touch panel 300 includes the light-emitting element (e.g., thelight-emitting element 350R) over the insulating film 321.

The touch panel 300 includes, over the insulating film 321, a partitionwall 328 that overlaps with an end portion of the lower electrode 351R(see FIG. 15C). In addition, a spacer 329 that controls the distancebetween the substrate 310 and the counter substrate 370 is provided overthe partition wall 328.

[Structure of Image Signal Line Driver Circuit]

The image signal line driver circuit 303 s(1) includes a transistor 303t and a capacitor 303 c. Note that the driver circuit can be formed inthe same process and over the same substrate as those of the pixelcircuits. As illustrated in FIG. 15B, the transistor 303 t may include asecond gate over the insulating film 321. The second gate may beelectrically connected to a gate of the transistor 303 t, or differentpotentials may be supplied thereto. The second gate may be provided in atransistor 308 t, the transistor 302 t, or the like if necessary.

[Structure of Imaging Pixel]

The imaging pixels 308 each include a photoelectric conversion element308 p and an imaging pixel circuit for sensing light received by thephotoelectric conversion element 308 p. The imaging pixel circuitincludes a transistor 308 t.

For example, a PIN photodiode can be used as the photoelectricconversion element 308 p.

[Structures of Other Components]

The touch panel 300 includes a wiring 311 through which a signal issupplied. The wiring 311 is provided with a terminal 319. Note that anFPC 309(1) through which a signal such as an image signal or asynchronization signal is supplied is electrically connected to theterminal 319.

Note that a printed wiring board (PWB) may be attached to the FPC309(1).

Transistors formed in the same process can be used as the transistor 302t, the transistor 303 t, and the transistor 308 t, and the like.

Transistors of a bottom-gate type, a top-gate type, or the like can beused.

As a gate, a source, and a drain of a transistor, and a wiring or anelectrode included in a touch panel, a single-layer structure or alayered structure using any of metals such as aluminum, titanium,chromium, nickel, copper, yttrium, zirconium, molybdenum, silver,tantalum, and tungsten, or an alloy containing any of these metals asits main component can be used. For example, a single-layer structure ofan aluminum film containing silicon, a two-layer structure in which analuminum film is stacked over a titanium film, a two-layer structure inwhich an aluminum film is stacked over a tungsten film, a two-layerstructure in which a copper film is stacked over acopper-magnesium-aluminum alloy film, a two-layer structure in which acopper film is stacked over a titanium film, a two-layer structure inwhich a copper film is stacked over a tungsten film, a three-layerstructure in which a titanium film or a titanium nitride film, analuminum film or a copper film, and a titanium film or a titaniumnitride film are stacked in this order, a three-layer structure in whicha molybdenum film or a molybdenum nitride film, an aluminum film or acopper film, and a molybdenum film or a molybdenum nitride film arestacked in this order, and the like can be given. Note that atransparent conductive material containing indium oxide, tin oxide, orzinc oxide may be used. Copper containing manganese is preferably usedbecause controllability of a shape by etching is increased.

An oxide semiconductor is preferably used as a semiconductor in which achannel of a transistor such as the transistor 302 t, the transistor 303t, or the transistor 308 t is formed. In particular, an oxidesemiconductor having a wider band gap than silicon is preferably used. Asemiconductor material having a wider band gap and a lower carrierdensity than silicon is preferably used because off-state leakagecurrent of the transistor can be reduced.

The oxide semiconductor preferably contains at least indium (In) or zinc(Zn), for example. The oxide semiconductor further preferably containsan In-M-Zn-based oxide (M is a metal such as Al, Ti, Ga, Ge, Y, Zr, Sn,La, Ce, or Hf).

As the semiconductor layer, it is particularly preferable to use anoxide semiconductor film including a plurality of crystal parts whosec-axes are aligned perpendicular to a surface on which the semiconductorlayer is formed or the top surface of the semiconductor layer and inwhich the adjacent crystal parts have no grain boundary.

There is no grain boundary in such an oxide semiconductor; therefore,generation of a crack in an oxide semiconductor film that is caused bystress when a display panel is bent is prevented. Such an oxidesemiconductor can thus be preferably used for a flexible display panelthat is used in a bent state, or the like.

The use of such materials for the semiconductor layer makes it possibleto provide a highly reliable transistor in which a change in theelectrical characteristics is suppressed.

Charge accumulated in a capacitor through a transistor can be held for along time because of the low off-state current of the transistor. Whensuch a transistor is used for a pixel, operation of a driver circuit canbe stopped while a gray scale of an image displayed in each displayregion is maintained. As a result, a display device with an extremelylow power consumption can be obtained.

Alternatively, silicon is preferably used as a semiconductor in which achannel of a transistor such as the transistor 302 t, the transistor 303t, or the transistor 308 t is formed. Although amorphous silicon may beused as silicon, silicon having crystallinity is particularly preferablyused. For example, microcrystalline silicon, polycrystalline silicon,single crystal silicon, or the like is preferably used. In particular,polycrystalline silicon can be formed at a lower temperature than singlecrystal silicon and has higher field effect mobility and higherreliability than amorphous silicon. When such a polycrystallinesemiconductor is used for a pixel, the aperture ratio of the pixel canbe improved. Even in the case where pixels are provided at extremelyhigh resolution, a gate driver circuit and a source driver circuit canbe formed over a substrate over which the pixels are formed, and thenumber of components of an electronic device can be reduced.

Here, a method for forming a flexible light-emitting panel is described.

For convenience, a structure including a pixel and a driver circuit, astructure including an optical member such as a color filter, astructure including a touch sensor, or a structure including afunctional member is referred to as an element layer. An element layerincludes a display element, for example, and may include a wiringelectrically connected to a display element or an element such as atransistor used in a pixel or a circuit in addition to the displayelement.

Here, a support provided with an insulating surface over which anelement layer is formed is called a base material.

As a method for forming an element layer over a flexible base material,there are a method in which an element layer is formed directly over abase material, and a method in which an element layer is formed over asupporting base material that has stiffness and then the element layeris separated from the supporting base material and transferred to thebase material.

In the case where a material of the base material can withstand heatingtemperature in the process for forming the element layer, it ispreferred that the element layer be formed directly over the basematerial, in which case a manufacturing process can be simplified. Atthis time, the element layer is preferably formed in a state where thebase material is fixed to the supporting base material, in which casethe transfer of the element layer in a device and between devices can beeasy.

In the case of employing the method in which the element layer is formedover the supporting base material and then transferred to the basematerial, first, a separation layer and an insulating layer are stackedover a supporting base material, and then the element layer is formedover the insulating layer. Then, the element layer is separated from thesupporting base material and then transferred to the base material. Atthis time, a material is selected such that separation at an interfacebetween the supporting base material and the separation layer, at aninterface between the separation layer and the insulating layer, or inthe separation layer occurs. With such a method, the element layer canbe formed at temperatures higher than the upper temperature limit of thebase material, which improves the reliability.

For example, it is preferable that a stacked layer of a layer includinga high-melting-point metal material, such as tungsten, and a layerincluding an oxide of the metal material be used as the separationlayer, and a stacked layer of a plurality of layers as the insulatinglayer, such as a silicon nitride layer and a silicon oxynitride layer beused over the separation layer. By using a high-melting-point metalmaterial, a high-temperature process can be performed to form theelement layer, resulting in high reliability. For example, impuritiescontained in the element layer can be further reduced, and thecrystallinity of a semiconductor or the like included in the elementlayer can be further increased.

Examples of the separation include peeling off by application ofmechanical power, removal of the separation layer by etching, orseparation by dripping of a liquid into part of the separation interfaceto penetrate the entire separation interface.

The separation layer is not necessarily provided in the case whereseparation can occur at an interface between the supporting basematerial and the insulating layer. For example, glass may be used as thesupporting base material, an organic resin such as polyimide may be usedas the insulating layer, a separation trigger may be formed by locallyheating part of the organic resin by laser light or the like, andseparation may be performed at an interface between the glass and theinsulating layer. Alternatively, it is possible that a layer containinga material with high thermal conductivity (e.g., a metal or asemiconductor) is provided between the supporting base material and theinsulating layer containing an organic resin, and this layer is heatedby current so that separation easily occurs, and then separation isperformed. In this case, the insulating layer containing an organicresin can also be used as the base material.

Examples of materials of such a flexible base material include polyesterresins such as polyethylene terephthalate (PET) and polyethylenenaphthalate (PEN), a polyacrylonitrile resin, a polyimide resin, apolymethyl methacrylate resin, a polycarbonate (PC) resin, apolyethersulfone (PES) resin, a polytetrafluoroethylene (PTFE) resin, apolyamide resin, a cycloolefin resin, a polystyrene resin, a polyamideimide resin, and a polyvinyl chloride resin. In particular, a materialwhose thermal expansion coefficient is low, for example, lower than orequal to 30×10⁻⁶/K is preferably used, and a polyamide imide resin, apolyimide resin, PET, or the like can suitably be used. Alternatively, asubstrate in which a fibrous body is impregnated with a resin (alsoreferred to as prepreg) or a substrate whose thermal expansioncoefficient is reduced by mixing an inorganic filler with an organicresin can be used.

In the case where a fibrous body is included in the above material, ahigh-strength fiber of an organic compound or an inorganic compound ispreferably used as the fibrous body. The high-strength fiber isspecifically a fiber with a high tensile modulus of elasticity or afiber with a high Young's modulus. Typical examples thereof include apolyvinyl alcohol-based fiber, a polyester-based fiber, apolyamide-based fiber, a polyethylene-based fiber, an aramid-basedfiber, a polyparaphenylene benzobisoxazole fiber, a glass fiber, and acarbon fiber. As the glass fiber, glass fiber using E glass, S glass, Dglass, Q glass, or the like can be used. These fibers may be used in astate of a woven fabric or a nonwoven fabric, and a structure body inwhich this fibrous body is impregnated with a resin and the resin iscured may be used as the flexible substrate. The structure bodyincluding the fibrous body and the resin is preferably used as theflexible substrate, in which case the reliability against bending orbreaking due to local pressure can be increased.

Note that for a display device of one embodiment of the presentinvention, an active matrix method in which an active element isincluded in a pixel or a passive matrix method in which an activeelement is not included in a pixel can be used.

In an active matrix method, as an active element (a non-linear element),not only a transistor but also various active elements (non-linearelements) can be used. For example, a metal insulator metal (MIM), athin film diode (TFD), or the like can be used. Such an element has fewnumbers of manufacturing steps; thus, the manufacturing cost can bereduced or yield can be improved. Furthermore, because the size of theelement is small, the aperture ratio can be improved, so that powerconsumption can be reduced or higher luminance can be achieved.

As a method other than the active matrix method, the passive matrixmethod in which an active element (a non-linear element) is not used maybe used. Since an active element (a non-linear element) is not used, thenumber of manufacturing steps is small, so that the manufacturing costcan be reduced or yield can be improved. Furthermore, since an activeelement (a non-linear element) is not used, the aperture ratio can beimproved, so that power consumption can be reduced or higher luminancecan be achieved, for example.

Note that an example of the case where a variety of display is performedusing the display device is shown here; however, one embodiment of thepresent invention is not limited thereto. For example, data is notnecessarily displayed. As an example, the display device may be used asa lighting device. By using the device as a lighting device, it can beused as interior lighting having an attractive design. Alternatively, itcan be used as lighting with which various directions can beilluminated. Further alternatively, it may be used as a light source,e.g., a backlight or a front light, not the display device. In otherwords, it may be used as a lighting device for the display panel.

Here, in particular, in the case where the display device of oneembodiment of the present invention is used for a television device forhome use, digital signage, and a PID, it is preferable to use a touchpanel for a display panel as described above because a device with sucha structure does not just display a still or moving image, but can beoperated by viewers intuitively. In the case where the display device ofone embodiment of the present invention is used for advertisement, theeffectiveness of the advertisement can be increased. Alternatively, inthe case where the display device of one embodiment of the presentinvention is used for providing information such as route informationand traffic information, usability can be enhanced by intuitiveoperation.

Note that in the case where a display panel does not need to function asa touch sensor, for example, in the case of using the display panel forlarge advertisements on the walls of buildings, public facilities, andthe like, the display panel may have a structure in which the structureof the touch sensor is omitted from the above structure example of thetouch panel.

Embodiment 3

In this embodiment, a display panel which can be used in the displaydevice of one embodiment of the present invention is described withreference to drawings.

Here, as an example of the display panel, a touch panel serving as atouch sensor is described.

FIGS. 16A to 16C are cross-sectional views of a touch panel 500.

The touch panel 500 includes a display portion 501 and a touch sensor595. The touch panel 500 further includes a substrate 510, a substrate570, and a substrate 590. Note that the substrate 510, the substrate570, and the substrate 590 each have flexibility.

The display portion 501 includes the substrate 510, a plurality ofpixels over the substrate 510, and a plurality of wirings 511 throughwhich signals are supplied to the pixels. The plurality of wirings 511is led to a peripheral portion of the substrate 510, and part of theplurality of wirings 511 forms a terminal 519. The terminal 519 iselectrically connected to an FPC 509(1).

[Touch Sensor]

The substrate 590 includes the touch sensor 595 and a plurality ofwirings 598 electrically connected to the touch sensor 595. Theplurality of wirings 598 is led to a peripheral portion of the substrate590, and part of the plurality of wirings 598 forms a terminal. Theterminal is electrically connected to an FPC 509(2).

As the touch sensor 595, a capacitive touch sensor can be used. Examplesof the capacitive touch sensor include a surface capacitive touch sensorand a projected capacitive touch sensor.

Examples of the projected capacitive touch sensor include a selfcapacitive touch sensor and a mutual capacitive touch sensor, whichdiffer mainly in the driving method. The use of a mutual capacitive typeis preferable because multiple points can be sensed simultaneously.

The case of using a projected capacitive touch sensor will be describedbelow.

Note that the structure of the touch sensor is not limited to the abovestructure, and a variety of sensors that can sense the proximity or thecontact of a sensing target such as a finger, can be used.

The projected capacitive touch sensor 595 includes electrodes 591 andelectrodes 592. The electrodes 591 are electrically connected to any ofthe plurality of wirings 598, and the electrodes 592 are electricallyconnected to any of the other wirings 598.

A wiring 594 electrically connects two electrodes 591 between which theelectrode 592 is positioned. The intersecting area of the electrode 592and the wiring 594 is preferably as small as possible. Such a structureallows a reduction in the area of a region where the electrodes are notprovided, reducing unevenness in transmittance. As a result, unevennessin the luminance of light penetrating the touch sensor 595 can bereduced.

Note that the electrodes 591 and the electrodes 592 can have any of avariety of shapes. For example, the plurality of electrodes 591 may beprovided such that space between the electrodes 591 are reduced as muchas possible, and the plurality of electrodes 592 may be provided with aninsulating layer sandwiched between the electrodes 591 and theelectrodes 592 and may be spaced apart from each other to form a regionnot overlapping with the electrodes 591. In that case, between twoadjacent electrodes 592, a dummy electrode that is electricallyinsulated from these electrodes is preferably provided, whereby the areaof a region having a different transmittance can be reduced.

The touch sensor 595 includes the substrate 590, the electrodes 591 andthe electrodes 592 provided in a staggered arrangement on the substrate590, an insulating layer 593 covering the electrodes 591 and theelectrodes 592, and the wiring 594 that electrically connects theadjacent electrodes 591.

An adhesive layer 597 bonds the substrate 590 to the substrate 570 suchthat the touch sensor 595 overlaps with the display portion 501.

The electrodes 591 and the electrodes 592 are formed using alight-transmitting conductive material. As the light-transmittingconductive material, a conductive oxide such as indium oxide, indium tinoxide, indium zinc oxide, zinc oxide, or zinc oxide to which gallium isadded, or graphene can be used. Alternatively, silver, copper, aluminum,a carbon nanotube, a metal halide (e.g., a silver halide), or the likemay be used. Further alternatively, a metal nanowire including a numberof conductors with an extremely small width (e.g., a diameter of severalnanometers), or a metal mesh which is a net-like conductor may be used.For example, an Ag nanowire, a Cu nanowire, an Al nanowire, an Ag mesh,a Cu mesh, or an Al mesh may be used. In the case of using an Agnanowire, light transmittance of 89% or more and a sheet resistance of40 ohm/square or more and 100 ohm/square or less can be achieved. Notethat because of having high transmittance, a metal nanowire, a metalmesh, a carbon nanotube, graphene, or the like may be used as anelectrode of the display element, such as a pixel electrode or a commonelectrode.

The electrodes 591 and the electrodes 592 can be formed by depositing alight-transmitting conductive material on the substrate 590 by asputtering method and then removing an unnecessary portion by any ofvarious patterning techniques such as photolithography. Graphene can beformed by a CVD method or in such a manner that a solution in whichgraphene oxide is dispersed is applied and reduced.

Examples of a material for the insulating layer 593 include resins suchas acrylic and an epoxy resin, a resin having a siloxane bond, andinorganic insulating materials such as silicon oxide, siliconoxynitride, and aluminum oxide.

Furthermore, openings reaching the electrodes 591 are formed in theinsulating layer 593, and the wiring 594 electrically connects theadjacent electrodes 591. A light-transmitting conductive material can befavorably used for the wiring 594 because the aperture ratio of thetouch panel can be increased. Moreover, a material with higherconductivity than those of the electrodes 591 and 592 can be favorablyused for the wiring 594 because electric resistance can be reduced.

One electrode 592 extends in one direction, and the plurality ofelectrodes 592 is provided in the form of stripes.

The wiring 594 intersects with the electrode 592.

Adjacent electrodes 591 are provided with one electrode 592 providedtherebetween. The wiring 594 electrically connects the adjacentelectrodes 591.

Note that the plurality of electrodes 591 is not necessarily arranged inthe direction orthogonal to one electrode 592 and may be arranged tointersect with one electrode 592 at an angle of less than 90 degrees.

One wiring 598 is electrically connected to any of the electrodes 591and 592. Part of the wiring 598 serves as a terminal. For the wiring598, a metal material such as aluminum, gold, platinum, silver, nickel,titanium, tungsten, chromium, molybdenum, iron, cobalt, copper, orpalladium or an alloy material containing any of these metal materialscan be used.

Note that an insulating layer that covers the insulating layer 593 andthe wiring 594 may be provided to protect the touch sensor 595.

A connection layer 599 electrically connects the wiring 598 to the FPC509(2).

As the connection layer 599, any of anisotropic conductive films (ACF),anisotropic conductive pastes (ACP), and the like can be used.

The adhesive layer 597 has a light-transmitting property. For example, athermosetting resin or an ultraviolet curable resin can be used;specifically, an acrylic resin, a urethane resin, an epoxy resin, or aresin having a siloxane bond can be used.

Note that the FPC 509(2), the light-blocking wiring electricallyconnected to the FPC 509(2), and the like may be placed not to overlapwith the region 110 transmitting visible light.

[Display Portion]

The display portion 501 includes a plurality of pixels arranged inmatrix. Each of the pixels includes a display element and a pixelcircuit for driving the display element.

In this embodiment, an example of using an organic electroluminescentelement that emits white light as a display element is described;however, the display element is not limited to such element.

Other than organic electroluminescent elements, for example, any ofvarious display elements such as display elements (electronic ink) thatperform display by an electrophoretic method, Electronic Liquid Powder®method, or the like; MEMS shutter display elements; andoptical-interference-type MEMS display elements can be used. Note that acircuit structure suitable for employed display elements can be selectedfrom among a variety of structures of pixel circuits.

The substrate 510 is a stack in which a flexible substrate 510 b, abarrier film 510 a that prevents diffusion of impurities tolight-emitting elements, and an adhesive layer 510 c that bonds thebarrier film 510 a to the substrate 510 b are stacked.

The substrate 570 is a stack in which a flexible substrate 570 b, abarrier film 570 a that prevents diffusion of impurities to thelight-emitting elements, and an adhesive layer 570 c that bonds thebarrier film 570 a to the substrate 570 b are stacked.

A sealant 560 bonds the substrate 570 to the substrate 510. The sealant560 has a refractive index higher than that of air. In the case ofextracting light to the sealant 560 side, the sealant 560 serves as anoptical adhesive layer. The pixel circuits and the light-emittingelements (e.g., a light-emitting element 550R) are provided between thesubstrate 510 and the substrate 570.

[Pixel Structure]

The pixel includes a sub-pixel 502R, and the sub-pixel 502R includes alight-emitting module 580R.

The sub-pixel 502R includes the light-emitting element 550R and thepixel circuit that can supply electric power to the light-emittingelement 550R and includes a transistor 502 t. The light-emitting module580R includes the light-emitting element 550R and an optical element(e.g., a coloring layer 567R).

The light-emitting element 550R includes a lower electrode, an upperelectrode, and a layer containing a light-emitting organic compoundbetween the lower electrode and the upper electrode.

The light-emitting module 580R includes the coloring layer 567R on thelight extraction side. The coloring layer transmits light with aparticular wavelength and is, for example, a layer that selectivelytransmits red, green, or blue light. Note that in another sub-pixel, aregion that transmits light emitted from the light-emitting element asit is may be provided.

In the case where the sealant 560 is provided on the light extractionside, the sealant 560 is in contact with the light-emitting element 550Rand the coloring layer 567R.

The coloring layer 567R is positioned in a region overlapping with thelight-emitting element 550R. Accordingly, part of light emitted from thelight-emitting element 550R passes through the coloring layer 567R andis emitted to the outside of the light-emitting module 580R as indicatedby an arrow in FIG. 16A.

[Structure of Display Portion]

The display portion 501 includes a light-blocking layer 567BM on thelight extraction side. The light-blocking layer 567BM is provided so asto surround the coloring layer (e.g., the coloring layer 567R).

The display portion 501 includes an anti-reflective layer 567 ppositioned in a region overlapping with the pixels. As theanti-reflective layer 567 p, a circular polarizing plate can be used,for example.

The display portion 501 includes an insulating film 521. The insulatingfilm 521 covers the transistor 502 t. Note that the insulating film 521can be used as a layer for planarizing unevenness due to the pixelcircuit. A layered film including a layer that can prevent diffusion ofimpurities can be used as the insulating film 521. This can preventdecrease of the reliability of the transistor 502 t or the like due todiffusion of impurities.

The display portion 501 includes the light-emitting elements (e.g., thelight-emitting element 550R) over the insulating film 521.

The display portion 501 includes, over the insulating film 521, apartition wall 528 that overlaps with an end portion of the lowerelectrode. In addition, a spacer that controls the distance between thesubstrate 510 and the substrate 570 is provided over the partition wall528.

[Configuration of Scan Line Driver Circuit]

A scan line driver circuit 503 g(1) includes a transistor 503 t and acapacitor 503 c. Note that the driver circuit can be formed in the sameprocess and over the same substrate as those of the pixel circuits.

[Structures of Other Components]

The display portion 501 includes the wirings 511 through which signalsare supplied. The wirings 511 are provided with the terminal 519. Notethat the FPC 509(1) through which a signal such as an image signal or asynchronization signal are supplied is electrically connected to theterminal 519.

Note that a printed wiring board (PWB) may be attached to the FPC509(1).

[Modification Example of Display Portion]

Any of various kinds of transistors can be used in the display portion501.

FIGS. 16A and 16B each illustrate a structure in which bottom-gatetransistors are used in the display portion 501.

For example, a semiconductor layer containing an oxide semiconductor,amorphous silicon, or the like can be used in the transistor 502 t andthe transistor 503 t illustrated in FIG. 16A.

For example, a semiconductor layer containing polycrystalline silicon orthe like can be used in the transistor 502 t and the transistor 503 tillustrated in FIG. 16B.

A structure of the case where top-gate transistors are used in thedisplay portion 501 is illustrated in FIG. 16C.

For example, a semiconductor layer containing an oxide semiconductor,polycrystalline silicon, a transferred single crystal silicon film, orthe like can be used in the transistor 502 t and the transistor 503 t inFIG. 16C.

At least part of this embodiment can be implemented in combination withany of the other embodiments described in this specification asappropriate.

Embodiment 4

In this embodiment, a display panel which can be used in a displaydevice of one embodiment of the present invention is described withreference to drawings. Here, as an example of the display panel, a touchpanel serving as a touch sensor is described.

FIGS. 17A to 17C are cross-sectional views of a touch panel 500B.

The touch panel 500B described in this embodiment is different from thetouch panel 500 described in Embodiment 3 in that the display portion501 displays received image data to the side where the transistors areprovided and that the touch sensor is provided on the substrate 510 sideof the display portion. Different structures will be described in detailbelow, and the above description is referred to for the other similarstructures.

[Display Portion]

The display portion 501 includes a plurality of pixels arranged inmatrix. Each of the pixels includes a display element and a pixelcircuit for driving the display element.

[Pixel Structure]

A pixel includes a sub-pixel 502R, and the sub-pixel 502R includes alight-emitting module 580R.

The sub-pixel 502R includes the light-emitting element 550R and thepixel circuit that can supply electric power to the light-emittingelement 550R and includes a transistor 502 t.

The light-emitting module 580R includes the light-emitting element 550Rand an optical element (e.g., the coloring layer 567R).

The light-emitting element 550R includes a lower electrode, an upperelectrode, and a layer containing a light-emitting organic compoundbetween the lower electrode and the upper electrode.

The light-emitting module 580R includes the coloring layer 567R on thelight extraction side. The coloring layer transmits light with aparticular wavelength and is, for example, a layer that selectivelytransmits red, green, or blue light. Note that in another sub-pixel, aregion that transmits light emitted from the light-emitting element asit is may be provided.

The coloring layer 567R is positioned in a region overlapping with thelight-emitting element 550R. The light-emitting element 550R illustratedin FIG. 17A emits light to the side where the transistor 502 t isprovided. Accordingly, part of light emitted from the light-emittingelement 550R passes through the coloring layer 567R and is emitted tothe outside of the light-emitting module 580R as indicated by an arrowin FIG. 17A.

[Structure of Display Portion]

The display portion 501 includes a light-blocking layer 567BM on thelight extraction side. The light-blocking layer 567BM is provided so asto surround the coloring layer (e.g., the coloring layer 567R).

The display portion 501 includes an insulating film 521. The insulatingfilm 521 covers the transistor 502 t. Note that the insulating film 521can be used as a layer for planarizing unevenness due to the pixelcircuit. A layered film including a layer that can prevent diffusion ofimpurities can be used as the insulating film 521. This can prevent thedecrease of the reliability of the transistor 502 t or the like due todiffusion of impurities from the coloring layer 567R.

[Touch Sensor]

The touch sensor 595 is provided on the substrate 510 side of thedisplay portion 501 (see FIG. 17A).

The adhesive layer 597 is provided between the substrate 510 and thesubstrate 590 and bonds the touch sensor 595 to the display portion 501.

Note that the FPC 509(2), the light-blocking wiring electricallyconnected to the FPC 509(2), and the like may be placed not to overlapwith the region 110 transmitting visible light.

[Modification Example of Display Portion]

Any of various kinds of transistors can be used in the display portion501.

FIGS. 17A and 17B illustrate a structure of the case where bottom-gatetransistors are used in the display portion 501.

For example, a semiconductor layer containing an oxide semiconductor,amorphous silicon, or the like can be used in the transistor 502 t andthe transistor 503 t illustrated in FIG. 17A.

For example, a semiconductor layer containing polycrystalline silicon orthe like can be used in the transistor 502 t and the transistor 503 tillustrated in FIG. 17B.

FIG. 17C illustrates a structure of the case where top-gate transistorsare used in the display portion 501.

For example, a semiconductor layer containing an oxide semiconductor,polycrystalline silicon, a transferred single crystal silicon film, orthe like can be used in the transistor 502 t and the transistor 503 tillustrated in FIG. 17C.

At least part of this embodiment can be implemented in combination withany of the other embodiments described in this specification asappropriate.

Embodiment 5

In this embodiment, application examples of a display device of oneembodiment of the present invention and electronic devices and the likeincluding display devices will be described.

As examples of electronic devices including a display device withflexibility, the following can be given: television devices (alsoreferred to as televisions or television receivers), monitors ofcomputers or the like, cameras such as digital cameras or digital videocameras, digital photo frames, mobile phones (also referred to as mobilephones or mobile phone devices), portable game machines, portableinformation terminals, audio reproducing devices, large game machinessuch as pachinko machines, and the like.

In addition, a lighting device or a display device can be incorporatedalong a curved inside/outside wall surface of a house or a building or acurved interior/exterior surface of a car.

In the display device 10 of one embodiment of the present invention, byincreasing the number of display panels 100, the area of the displayregion 11 can be increased unlimitedly. Thus, the display device 10 canbe favorably used for applications for displaying a large image, such asdigital signage and a PID. Furthermore, by changing the arrangement ofthe display panels 100, the contour of the display device 10 of oneembodiment of the present invention can have any of a variety of shapes.

FIG. 18 shows an example in which the display device 10 of oneembodiment of the present invention is provided for a column 15 and awall 16. A flexible display panel is used as the display panel 100included in the display device 10, whereby the display device 10 can beplaced along a curved surface.

The display device 10 of one embodiment of the present invention can beused in an electronic device such as a portable information terminal inthe case where a plurality of small-sized display panels 100 are used.

An electronic device of one embodiment of the present invention mayinclude a touch panel and a secondary battery. It is preferable that thesecondary battery is capable of being charged by contactless powertransmission.

As examples of the secondary battery, a lithium ion secondary batterysuch as a lithium polymer battery (lithium ion polymer battery) using agel electrolyte, a lithium ion battery, a nickel-hydride battery, anickel-cadmium battery, an organic radical battery, a lead-acid battery,an air secondary battery, a nickel-zinc battery, and a silver-zincbattery can be given.

The electronic device of one embodiment of the present invention mayinclude a touch panel and an antenna. When a signal is received by theantenna, the electronic device can display an image, data, or the likeon a display portion. When the electronic device includes a secondarybattery, the antenna may be used for contactless power transmission.

FIG. 19A illustrates an example of a mobile phone. The mobile phone 7400is provided with a display portion 7402 incorporated in a housing 7401,operation buttons 7403, an external connection port 7404, a speaker7405, a microphone 7406, and the like. Note that the mobile phone 7400is manufactured by using the touch panel of one embodiment of thepresent invention for the display portion 7402. In accordance with oneembodiment of the present invention, highly reliable mobile phones eachhaving a curved display portion can be provided at a high yield.

When the display portion 7402 of the mobile phone 7400 illustrated inFIG. 19A is touched with a finger or the like, data can be input intothe mobile phone 7400. Further, operations such as making a call andinputting a letter can be performed by touch on the display portion 7402with a finger or the like.

With the operation buttons 7403, power ON or OFF can be switched. Inaddition, types of images displayed on the display portion 7402 can beswitched; switching images from a mail creation screen to a main menuscreen.

FIG. 19B illustrates an example of a wrist-watch-type portableinformation terminal. A portable information terminal 7100 includes ahousing 7101, a display portion 7102, a band 7103, a buckle 7104, anoperation button 7105, an input/output terminal 7106, and the like.

The portable information terminal 7100 is capable of executing a varietyof applications such as mobile phone calls, e-mailing, reading andediting texts, music reproduction, Internet communication, and acomputer game.

The display surface of the display portion 7102 is bent, and images canbe displayed on the bent display surface. Furthermore, the displayportion 7102 includes a touch sensor, and operation can be performed bytouching the screen with a finger, a stylus, or the like. For example,by touching an icon 7107 displayed on the display portion 7102, anapplication can be started.

With the operation button 7105, a variety of functions such as timesetting, power ON/OFF, ON/OFF of wireless communication, setting andcancellation of manner mode, and setting and cancellation of powersaving mode can be performed. For example, the functions of theoperation button 7105 can be set freely by the operating systemincorporated in the portable information terminal 7100.

The portable information terminal 7100 can employ near fieldcommunication that is a communication method based on an existingcommunication standard. In that case, for example, mutual communicationbetween the portable information terminal 7100 and a headset capable ofwireless communication can be performed, and thus hands-free calling ispossible.

Moreover, the portable information terminal 7100 includes theinput/output terminal 7106, and data can be directly transmitted to andreceived from another information terminal via a connector. Chargingthrough the input/output terminal 7106 is possible. Note that thecharging operation may be performed by wireless power feeding withoutusing the input/output terminal 7106.

The display portion 7102 of the portable information terminal 7100includes the touch panel of one embodiment of the present invention.According to one embodiment of the present invention, highly reliableportable information terminals each having a curved display portion canbe provided with a high yield.

FIGS. 19C to 19E illustrate examples of lighting devices. Lightingdevices 7200, 7210, and 7220 each include a stage 7201 provided with anoperation switch 7203 and a light-emitting portion supported by thestage 7201.

The lighting device 7200 illustrated in FIG. 19C includes alight-emitting portion 7202 with a wave-shaped light-emitting surfaceand thus is a good-design lighting device.

A light-emitting portion 7212 included in the lighting device 7210illustrated in FIG. 19D has two convex-curved light-emitting portionssymmetrically placed. Thus, all directions can be illuminated with thelighting device 7210 as a center.

The lighting device 7220 illustrated in FIG. 19E includes aconcave-curved light-emitting portion 7222. This is suitable forilluminating a specific range because light emitted from thelight-emitting portion 7222 is collected to the front of the lightingdevice 7220.

The light-emitting portion included in each of the lighting devices7200, 7210, and 7220 are flexible; thus, the light-emitting portion maybe fixed on a plastic member, a movable frame, or the like so that anemission surface of the light-emitting portion can be bent freelydepending on the intended use.

Note that although the lighting device in which the light-emittingportion is supported by the stage is described as an example here, ahousing provided with a light-emitting portion can be fixed on a ceilingor suspended from a ceiling. Since the light-emitting surface can becurved, the light-emitting surface is curved to have a depressed shape,whereby a particular region can be brightly illuminated, or thelight-emitting surface is curved to have a projecting shape, whereby awhole room can be brightly illuminated.

Here, the light-emitting portions each include the touch panel of oneembodiment of the present invention. In accordance with one embodimentof the present invention, highly reliable lighting devices each having acurved light-emitting portion can be provided at a high yield.

FIG. 19F illustrates an example of a portable touch panel. A touch panel7300 includes a housing 7301, a display portion 7302, operation buttons7303, a display portion pull 7304, and a control portion 7305.

The touch panel 7300 includes a rolled flexible display portion 7302 inthe cylindrical housing 7301.

The touch panel 7300 can receive a video signal with the control portion7305 and can display the received video on the display portion 7302. Inaddition, a battery is included in the control portion 7305. Moreover, aterminal portion for connecting a connector may be included in thecontrol portion 7305 so that a video signal or power can be directlysupplied from the outside with a wiring.

By pressing the operation buttons 7303, power ON/OFF, switching ofdisplayed videos, and the like can be performed.

FIG. 19G illustrates a touch panel 7300 in a state where the displayportion 7302 is pulled out with the display portion pull 7304. Videoscan be displayed on the display portion 7302 in this state. Further, theoperation buttons 7303 on the surface of the housing 7301 allowone-handed operation. The operation button 7303 is provided not in thecenter of the housing 7301 but on one side of the housing 7301 asillustrated in FIG. 19F, which makes one-handed operation easy.

Note that a reinforcement frame may be provided for a side portion ofthe display portion 7302 so that the display portion 7302 has a flatdisplay surface when pulled out.

Note that in addition to this structure, a speaker may be provided forthe housing so that sound is output with an audio signal receivedtogether with a video signal.

The display portion 7302 includes the touch panel of one embodiment ofthe present invention. According to one embodiment of the presentinvention, lightweight and highly reliable touch panels can be providedwith a high yield.

At least part of this embodiment can be implemented in combination withany of the embodiments described in this specification as appropriate.

This application is based on Japanese Patent Application serial no.2014-147636 filed with Japan Patent Office on Jul. 18, 2014, the entirecontents of which are hereby incorporated by reference.

What is claimed is:
 1. (canceled)
 2. A display device comprising: afirst display panel; and a second display panel over a portion of thefirst display panel, wherein each of the first display panel and thesecond display panel comprises a display portion and a regiontransmitting visible light, wherein the display portion of the firstdisplay panel includes a first region which is not overlapped with thesecond display panel, wherein the display portion of the first displaypanel includes a second region which is overlapped with the regiontransmitting visible light of the second display panel, wherein thefirst region includes a first pixel and the second region includes asecond pixel, and wherein an aperture ratio of the second pixel ishigher than an aperture ratio of the first pixel.
 3. A display devicecomprising: a first display panel; and a second display panel over aportion of the first display panel, wherein each of the first displaypanel and the second display panel comprises a display portion and aregion transmitting visible light, wherein the display portion of thefirst display panel includes a first region which is not overlapped withthe second display panel, wherein the display portion of the firstdisplay panel includes a second region which is overlapped with theregion transmitting visible light of the second display panel, whereinthe first region includes a first pixel and the second region includes asecond pixel, wherein the first pixel includes a first display elementand a light-blocking layer including a first opening, wherein the firstopening is overlapped with the first display element, wherein the secondpixel includes a second display element and a light-blocking layerincluding a second opening, wherein the second opening is overlappedwith the second display element, and wherein an area of the secondopening is larger than an area of the first opening.
 4. The displaydevice according to claim 2, further comprising a third display panelcomprising a display portion and a region transmitting visible light,wherein the display portion of the second display panel includes a thirdregion which is not overlapped with the third display panel, wherein thedisplay portion of the second display panel includes a fourth regionwhich is overlapped with the region transmitting visible light of thethird display panel, wherein the third region includes a third pixel andthe fourth region includes a fourth pixel, and wherein an aperture ratioof the fourth pixel is higher than an aperture ratio of the third pixel.5. The display device according to claim 2, wherein each of the firstdisplay panel and the second display panel comprises a region blockingvisible light, wherein the region blocking visible light in the portionof the first display panel overlaps with the display portion of thesecond display panel, and wherein the region blocking visible light ofthe second display panel does not overlap with the display portion ofthe first display panel.
 6. The display device according to claim 2,further comprising a first FPC electrically connected to the firstdisplay panel and a second FPC electrically connected to the seconddisplay panel, wherein the first FPC is between the first display paneland the second display panel.
 7. The display device according to claim2, wherein each of the first display panel and the second display panelcomprises a substrate, and wherein the substrate has flexibility.
 8. Adisplay module comprising: the display device according to claim 2; anda touch sensor.
 9. An electronic device comprising: the display deviceaccording to claim 2; and a housing, wherein the housing includes atleast one of a button, a microphone, a speaker, an antenna, and abattery.
 10. The display device according to claim 3, further comprisinga third display panel comprising a display portion and a regiontransmitting visible light, wherein the display portion of the seconddisplay panel includes a third region which is not overlapped with thethird display panel, wherein the display portion of the second displaypanel includes a fourth region which is overlapped with the regiontransmitting visible light of the third display panel, wherein the thirdregion includes a third pixel and the fourth region includes a fourthpixel, and wherein an aperture ratio of the fourth pixel is higher thanan aperture ratio of the third pixel.
 11. The display device accordingto claim 3, wherein each of the first display panel and the seconddisplay panel comprises a region blocking visible light, wherein theregion blocking visible light in the portion of the first display paneloverlaps with the display portion of the second display panel, andwherein the region blocking visible light of the second display paneldoes not overlap with the display portion of the first display panel.12. The display device according to claim 3, further comprising a firstFPC electrically connected to the first display panel and a second FPCelectrically connected to the second display panel, wherein the firstFPC is between the first display panel and the second display panel. 13.The display device according to claim 3, wherein each of the firstdisplay panel and the second display panel comprises a substrate, andwherein the substrate has flexibility.
 14. A display module comprising:the display device according to claim 3; and a touch sensor.
 15. Anelectronic device comprising: the display device according to claim 3;and a housing, wherein the housing includes at least one of a button, amicrophone, a speaker, an antenna, and a battery.
 16. The display deviceaccording to claim 3, wherein the first display element and the seconddisplay element are light-emitting elements or liquid crystal elements.